Systemic lupus erythematosus (SLE), also known as lupus, is an autoimmune illness.
Although there are several different forms of lupus, the classical lupus patient is usually a young woman with a combination of symptoms, such as fever, swollen lymph glands, rashes (particularly butterfly-shaped rashes on the face), arthritis, fatigue, hair loss, chest and/or abdominal pain, oral ulcers, and neuropsychiatric problems, such as headache, memory loss, mood disorders, and/or confusion.
While the cause of lupus is unknown, theories on its origin include genetics, environment, infections, and the defective failure to process the products of an immune response. Although it is a lifelong condition, symptoms tend to cycle in alternate periods of flares and remission. Those with lupus are at great risk of contracting kidney disease as well.
Treatment options include corticosteroids, anti-malarial drugs, immunosuppressive drugs such as mycophenolate mofetil, cytotoxic agents such as cyclophosphamide, non-steroidal anti-inflammatory drugs (NSAIDs), and certain biologics, such as belimumab, rituximab, and others.
The American College of Rheumatology has established criteria that is used for studies, but can also aid in the diagnosis. If four or more of the eleven criteria occur, a patient may have SLE. These criteria are:                1. Malar rash (rash on cheeks);        2. Discoid rash (red, scaly patches on skin that cause scarring);        3. Photosensitivity;        4. Oral ulcers;        5. Nonerosive arthritis of two or more peripheral joints, with tenderness, swelling, or effusion;        6. Pleuritis or pericarditis;        7. Renal disorder as evidenced by more than 0.5 g per day protein in urine or cellular casts seen in urine under a microscope;        8. Neurologic disorder such as seizures or psychosis;        9. Hematalogic disorder such as hemolytic anemia (low red blood cell count) or leukopenia (white blood cell count<4000/μl);        10. Immunologic disorder including positive anti-smith, anti-ds DNA, anti-phospholipid antibody, and/or false positive serological test for syphilis; and        11. Positive anti-nuclear antibody (ANA) test.        
Currently, a number of tests are performed to aid in establishing a diagnosis of SLE in the context of the characteristic symptoms and signs of SLE. These include: antinuclear antibody (ANA) blood test; anti-double stranded DNA test; anti-Smith antibody test; VDRL, a syphilis test; complete blood count (CBC); blood chemistry levels; inflammatory markers—the erythrocyte sedimentation rate (also called the ESR) and C-reactive protein; x-rays of joints; and a biopsy from the skin or kidneys.
At this time there is no definitive diagnostic test for SLE, or any tests that predict the course and severity of the disease or which organs the disease is most likely to affect. Moreover, genetic testing is not routinely performed in order to diagnose SLE. Thus, there is a real need in the art for definitive tests to determine the severity of a patient's SLE, including the number and severity of flares of the disease. Moreover, with the vast number of etiologies of the disease, as well as the number of therapies used for treatment, a test that provides information on which organs and organ systems the disease will most affect would be useful. Better knowledge as to targets to concentrate upon when testing for drugs, as well as when performing basic research on SLE would be of great value as well.
The biomarkers described herein provide not only a novel and unique way to definitively screen, identify, and predict the severity, activity, and clinical manifestations of SLE, but provide a number of markers for use in drug screening and research, and basic research on SLE.